2 * This program is free software; you can redistribute it and/or modify it
3 * under the terms of the GNU General Public License as published by the
4 * Free Software Foundation; either version 2, or (at your option) any
7 * This program is distributed in the hope that it will be useful, but
8 * WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
10 * General Public License for more details.
15 * Copyright (C) 2004 Amit S. Kale <amitkale@linsyssoft.com>
16 * Copyright (C) 2000-2001 VERITAS Software Corporation.
17 * Copyright (C) 2002 Andi Kleen, SuSE Labs
18 * Copyright (C) 2004 LinSysSoft Technologies Pvt. Ltd.
19 * Copyright (C) 2007 MontaVista Software, Inc.
20 * Copyright (C) 2007-2008 Jason Wessel, Wind River Systems, Inc.
22 /****************************************************************************
23 * Contributor: Lake Stevens Instrument Division$
24 * Written by: Glenn Engel $
25 * Updated by: Amit Kale<akale@veritas.com>
26 * Updated by: Tom Rini <trini@kernel.crashing.org>
27 * Updated by: Jason Wessel <jason.wessel@windriver.com>
28 * Modified for 386 by Jim Kingdon, Cygnus Support.
29 * Origianl kgdb, compatibility with 2.1.xx kernel by
30 * David Grothe <dave@gcom.com>
31 * Integrated into 2.2.5 kernel by Tigran Aivazian <tigran@sco.com>
32 * X86_64 changes from Andi Kleen's patch merged by Jim Houston
34 #include <linux/spinlock.h>
35 #include <linux/kdebug.h>
36 #include <linux/string.h>
37 #include <linux/kernel.h>
38 #include <linux/ptrace.h>
39 #include <linux/sched.h>
40 #include <linux/delay.h>
41 #include <linux/kgdb.h>
42 #include <linux/init.h>
43 #include <linux/smp.h>
44 #include <linux/nmi.h>
45 #include <linux/hw_breakpoint.h>
47 #include <asm/debugreg.h>
48 #include <asm/apicdef.h>
49 #include <asm/system.h>
53 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
56 { "ax", 4, offsetof(struct pt_regs, ax) },
57 { "cx", 4, offsetof(struct pt_regs, cx) },
58 { "dx", 4, offsetof(struct pt_regs, dx) },
59 { "bx", 4, offsetof(struct pt_regs, bx) },
60 { "sp", 4, offsetof(struct pt_regs, sp) },
61 { "bp", 4, offsetof(struct pt_regs, bp) },
62 { "si", 4, offsetof(struct pt_regs, si) },
63 { "di", 4, offsetof(struct pt_regs, di) },
64 { "ip", 4, offsetof(struct pt_regs, ip) },
65 { "flags", 4, offsetof(struct pt_regs, flags) },
66 { "cs", 4, offsetof(struct pt_regs, cs) },
67 { "ss", 4, offsetof(struct pt_regs, ss) },
68 { "ds", 4, offsetof(struct pt_regs, ds) },
69 { "es", 4, offsetof(struct pt_regs, es) },
73 { "ax", 8, offsetof(struct pt_regs, ax) },
74 { "bx", 8, offsetof(struct pt_regs, bx) },
75 { "cx", 8, offsetof(struct pt_regs, cx) },
76 { "dx", 8, offsetof(struct pt_regs, dx) },
77 { "si", 8, offsetof(struct pt_regs, dx) },
78 { "di", 8, offsetof(struct pt_regs, di) },
79 { "bp", 8, offsetof(struct pt_regs, bp) },
80 { "sp", 8, offsetof(struct pt_regs, sp) },
81 { "r8", 8, offsetof(struct pt_regs, r8) },
82 { "r9", 8, offsetof(struct pt_regs, r9) },
83 { "r10", 8, offsetof(struct pt_regs, r10) },
84 { "r11", 8, offsetof(struct pt_regs, r11) },
85 { "r12", 8, offsetof(struct pt_regs, r12) },
86 { "r13", 8, offsetof(struct pt_regs, r13) },
87 { "r14", 8, offsetof(struct pt_regs, r14) },
88 { "r15", 8, offsetof(struct pt_regs, r15) },
89 { "ip", 8, offsetof(struct pt_regs, ip) },
90 { "flags", 4, offsetof(struct pt_regs, flags) },
91 { "cs", 4, offsetof(struct pt_regs, cs) },
92 { "ss", 4, offsetof(struct pt_regs, ss) },
96 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
100 regno == GDB_SS || regno == GDB_FS || regno == GDB_GS ||
102 regno == GDB_SP || regno == GDB_ORIG_AX)
105 if (dbg_reg_def[regno].offset != -1)
106 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
107 dbg_reg_def[regno].size);
111 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
113 if (regno == GDB_ORIG_AX) {
114 memcpy(mem, ®s->orig_ax, sizeof(regs->orig_ax));
117 if (regno >= DBG_MAX_REG_NUM || regno < 0)
120 if (dbg_reg_def[regno].offset != -1)
121 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
122 dbg_reg_def[regno].size);
127 if (!user_mode_vm(regs))
128 *(unsigned long *)mem = __KERNEL_DS;
131 if (!user_mode_vm(regs))
132 *(unsigned long *)mem = kernel_stack_pointer(regs);
136 *(unsigned long *)mem = 0xFFFF;
140 return dbg_reg_def[regno].name;
144 * sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
145 * @gdb_regs: A pointer to hold the registers in the order GDB wants.
146 * @p: The &struct task_struct of the desired process.
148 * Convert the register values of the sleeping process in @p to
149 * the format that GDB expects.
150 * This function is called when kgdb does not have access to the
151 * &struct pt_regs and therefore it should fill the gdb registers
152 * @gdb_regs with what has been saved in &struct thread_struct
153 * thread field during switch_to.
155 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
157 #ifndef CONFIG_X86_32
158 u32 *gdb_regs32 = (u32 *)gdb_regs;
160 gdb_regs[GDB_AX] = 0;
161 gdb_regs[GDB_BX] = 0;
162 gdb_regs[GDB_CX] = 0;
163 gdb_regs[GDB_DX] = 0;
164 gdb_regs[GDB_SI] = 0;
165 gdb_regs[GDB_DI] = 0;
166 gdb_regs[GDB_BP] = *(unsigned long *)p->thread.sp;
168 gdb_regs[GDB_DS] = __KERNEL_DS;
169 gdb_regs[GDB_ES] = __KERNEL_DS;
170 gdb_regs[GDB_PS] = 0;
171 gdb_regs[GDB_CS] = __KERNEL_CS;
172 gdb_regs[GDB_PC] = p->thread.ip;
173 gdb_regs[GDB_SS] = __KERNEL_DS;
174 gdb_regs[GDB_FS] = 0xFFFF;
175 gdb_regs[GDB_GS] = 0xFFFF;
177 gdb_regs32[GDB_PS] = *(unsigned long *)(p->thread.sp + 8);
178 gdb_regs32[GDB_CS] = __KERNEL_CS;
179 gdb_regs32[GDB_SS] = __KERNEL_DS;
180 gdb_regs[GDB_PC] = 0;
181 gdb_regs[GDB_R8] = 0;
182 gdb_regs[GDB_R9] = 0;
183 gdb_regs[GDB_R10] = 0;
184 gdb_regs[GDB_R11] = 0;
185 gdb_regs[GDB_R12] = 0;
186 gdb_regs[GDB_R13] = 0;
187 gdb_regs[GDB_R14] = 0;
188 gdb_regs[GDB_R15] = 0;
190 gdb_regs[GDB_SP] = p->thread.sp;
193 static struct hw_breakpoint {
198 struct perf_event * __percpu *pev;
199 } breakinfo[HBP_NUM];
201 static unsigned long early_dr7;
203 static void kgdb_correct_hw_break(void)
207 for (breakno = 0; breakno < HBP_NUM; breakno++) {
208 struct perf_event *bp;
209 struct arch_hw_breakpoint *info;
211 int cpu = raw_smp_processor_id();
212 if (!breakinfo[breakno].enabled)
215 set_debugreg(breakinfo[breakno].addr, breakno);
216 early_dr7 |= encode_dr7(breakno,
217 breakinfo[breakno].len,
218 breakinfo[breakno].type);
219 set_debugreg(early_dr7, 7);
222 bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
223 info = counter_arch_bp(bp);
224 if (bp->attr.disabled != 1)
226 bp->attr.bp_addr = breakinfo[breakno].addr;
227 bp->attr.bp_len = breakinfo[breakno].len;
228 bp->attr.bp_type = breakinfo[breakno].type;
229 info->address = breakinfo[breakno].addr;
230 info->len = breakinfo[breakno].len;
231 info->type = breakinfo[breakno].type;
232 val = arch_install_hw_breakpoint(bp);
234 bp->attr.disabled = 0;
237 hw_breakpoint_restore();
240 static int hw_break_reserve_slot(int breakno)
244 struct perf_event **pevent;
249 for_each_online_cpu(cpu) {
251 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
252 if (dbg_reserve_bp_slot(*pevent))
259 for_each_online_cpu(cpu) {
263 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
264 dbg_release_bp_slot(*pevent);
269 static int hw_break_release_slot(int breakno)
271 struct perf_event **pevent;
277 for_each_online_cpu(cpu) {
278 pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
279 if (dbg_release_bp_slot(*pevent))
281 * The debugger is responsible for handing the retry on
290 kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
294 for (i = 0; i < HBP_NUM; i++)
295 if (breakinfo[i].addr == addr && breakinfo[i].enabled)
300 if (hw_break_release_slot(i)) {
301 printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
304 breakinfo[i].enabled = 0;
309 static void kgdb_remove_all_hw_break(void)
312 int cpu = raw_smp_processor_id();
313 struct perf_event *bp;
315 for (i = 0; i < HBP_NUM; i++) {
316 if (!breakinfo[i].enabled)
318 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
319 if (!bp->attr.disabled) {
320 arch_uninstall_hw_breakpoint(bp);
321 bp->attr.disabled = 1;
325 early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
327 else if (hw_break_release_slot(i))
328 printk(KERN_ERR "KGDB: hw bpt remove failed %lx\n",
330 breakinfo[i].enabled = 0;
335 kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
339 for (i = 0; i < HBP_NUM; i++)
340 if (!breakinfo[i].enabled)
346 case BP_HARDWARE_BREAKPOINT:
348 breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
350 case BP_WRITE_WATCHPOINT:
351 breakinfo[i].type = X86_BREAKPOINT_WRITE;
353 case BP_ACCESS_WATCHPOINT:
354 breakinfo[i].type = X86_BREAKPOINT_RW;
361 breakinfo[i].len = X86_BREAKPOINT_LEN_1;
364 breakinfo[i].len = X86_BREAKPOINT_LEN_2;
367 breakinfo[i].len = X86_BREAKPOINT_LEN_4;
371 breakinfo[i].len = X86_BREAKPOINT_LEN_8;
377 breakinfo[i].addr = addr;
378 if (hw_break_reserve_slot(i)) {
379 breakinfo[i].addr = 0;
382 breakinfo[i].enabled = 1;
388 * kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
389 * @regs: Current &struct pt_regs.
391 * This function will be called if the particular architecture must
392 * disable hardware debugging while it is processing gdb packets or
393 * handling exception.
395 static void kgdb_disable_hw_debug(struct pt_regs *regs)
398 int cpu = raw_smp_processor_id();
399 struct perf_event *bp;
401 /* Disable hardware debugging while we are in kgdb: */
402 set_debugreg(0UL, 7);
403 for (i = 0; i < HBP_NUM; i++) {
404 if (!breakinfo[i].enabled)
407 early_dr7 &= ~encode_dr7(i, breakinfo[i].len,
411 bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
412 if (bp->attr.disabled == 1)
414 arch_uninstall_hw_breakpoint(bp);
415 bp->attr.disabled = 1;
421 * kgdb_roundup_cpus - Get other CPUs into a holding pattern
422 * @flags: Current IRQ state
424 * On SMP systems, we need to get the attention of the other CPUs
425 * and get them be in a known state. This should do what is needed
426 * to get the other CPUs to call kgdb_wait(). Note that on some arches,
427 * the NMI approach is not used for rounding up all the CPUs. For example,
428 * in case of MIPS, smp_call_function() is used to roundup CPUs. In
429 * this case, we have to make sure that interrupts are enabled before
430 * calling smp_call_function(). The argument to this function is
431 * the flags that will be used when restoring the interrupts. There is
432 * local_irq_save() call before kgdb_roundup_cpus().
434 * On non-SMP systems, this is not called.
436 void kgdb_roundup_cpus(unsigned long flags)
438 apic->send_IPI_allbutself(APIC_DM_NMI);
443 * kgdb_arch_handle_exception - Handle architecture specific GDB packets.
444 * @vector: The error vector of the exception that happened.
445 * @signo: The signal number of the exception that happened.
446 * @err_code: The error code of the exception that happened.
447 * @remcom_in_buffer: The buffer of the packet we have read.
448 * @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
449 * @regs: The &struct pt_regs of the current process.
451 * This function MUST handle the 'c' and 's' command packets,
452 * as well packets to set / remove a hardware breakpoint, if used.
453 * If there are additional packets which the hardware needs to handle,
454 * they are handled here. The code should return -1 if it wants to
455 * process more packets, and a %0 or %1 if it wants to exit from the
458 int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
459 char *remcomInBuffer, char *remcomOutBuffer,
460 struct pt_regs *linux_regs)
465 switch (remcomInBuffer[0]) {
468 /* try to read optional parameter, pc unchanged if no parm */
469 ptr = &remcomInBuffer[1];
470 if (kgdb_hex2long(&ptr, &addr))
471 linux_regs->ip = addr;
474 /* clear the trace bit */
475 linux_regs->flags &= ~X86_EFLAGS_TF;
476 atomic_set(&kgdb_cpu_doing_single_step, -1);
478 /* set the trace bit if we're stepping */
479 if (remcomInBuffer[0] == 's') {
480 linux_regs->flags |= X86_EFLAGS_TF;
481 atomic_set(&kgdb_cpu_doing_single_step,
482 raw_smp_processor_id());
488 /* this means that we do not want to exit from the handler: */
493 single_step_cont(struct pt_regs *regs, struct die_args *args)
496 * Single step exception from kernel space to user space so
497 * eat the exception and continue the process:
499 printk(KERN_ERR "KGDB: trap/step from kernel to user space, "
501 kgdb_arch_handle_exception(args->trapnr, args->signr,
502 args->err, "c", "", regs);
504 * Reset the BS bit in dr6 (pointed by args->err) to
505 * denote completion of processing
507 (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
512 static int was_in_debug_nmi[NR_CPUS];
514 static int kgdb_nmi_handler(unsigned int cmd, struct pt_regs *regs)
518 if (atomic_read(&kgdb_active) != -1) {
519 /* KGDB CPU roundup */
520 kgdb_nmicallback(raw_smp_processor_id(), regs);
521 was_in_debug_nmi[raw_smp_processor_id()] = 1;
522 touch_nmi_watchdog();
528 if (was_in_debug_nmi[raw_smp_processor_id()]) {
529 was_in_debug_nmi[raw_smp_processor_id()] = 0;
540 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
542 struct pt_regs *regs = args->regs;
546 if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
548 return single_step_cont(regs, args);
550 } else if (test_thread_flag(TIF_SINGLESTEP))
551 /* This means a user thread is single stepping
552 * a system call which should be ignored
561 if (kgdb_handle_exception(args->trapnr, args->signr, cmd, regs))
564 /* Must touch watchdog before return to normal operation */
565 touch_nmi_watchdog();
569 int kgdb_ll_trap(int cmd, const char *str,
570 struct pt_regs *regs, long err, int trap, int sig)
572 struct die_args args = {
581 if (!kgdb_io_module_registered)
584 return __kgdb_notify(&args, cmd);
588 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
593 local_irq_save(flags);
594 ret = __kgdb_notify(ptr, cmd);
595 local_irq_restore(flags);
600 static struct notifier_block kgdb_notifier = {
601 .notifier_call = kgdb_notify,
605 * kgdb_arch_init - Perform any architecture specific initalization.
607 * This function will handle the initalization of any architecture
608 * specific callbacks.
610 int kgdb_arch_init(void)
614 retval = register_die_notifier(&kgdb_notifier);
618 retval = register_nmi_handler(NMI_LOCAL, kgdb_nmi_handler,
623 retval = register_nmi_handler(NMI_UNKNOWN, kgdb_nmi_handler,
632 unregister_nmi_handler(NMI_LOCAL, "kgdb");
634 unregister_die_notifier(&kgdb_notifier);
639 static void kgdb_hw_overflow_handler(struct perf_event *event,
640 struct perf_sample_data *data, struct pt_regs *regs)
642 struct task_struct *tsk = current;
645 for (i = 0; i < 4; i++)
646 if (breakinfo[i].enabled)
647 tsk->thread.debugreg6 |= (DR_TRAP0 << i);
650 void kgdb_arch_late(void)
653 struct perf_event_attr attr;
654 struct perf_event **pevent;
657 * Pre-allocate the hw breakpoint structions in the non-atomic
658 * portion of kgdb because this operation requires mutexs to
661 hw_breakpoint_init(&attr);
662 attr.bp_addr = (unsigned long)kgdb_arch_init;
663 attr.bp_len = HW_BREAKPOINT_LEN_1;
664 attr.bp_type = HW_BREAKPOINT_W;
666 for (i = 0; i < HBP_NUM; i++) {
667 if (breakinfo[i].pev)
669 breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL, NULL);
670 if (IS_ERR((void * __force)breakinfo[i].pev)) {
671 printk(KERN_ERR "kgdb: Could not allocate hw"
672 "breakpoints\nDisabling the kernel debugger\n");
673 breakinfo[i].pev = NULL;
677 for_each_online_cpu(cpu) {
678 pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
679 pevent[0]->hw.sample_period = 1;
680 pevent[0]->overflow_handler = kgdb_hw_overflow_handler;
681 if (pevent[0]->destroy != NULL) {
682 pevent[0]->destroy = NULL;
683 release_bp_slot(*pevent);
690 * kgdb_arch_exit - Perform any architecture specific uninitalization.
692 * This function will handle the uninitalization of any architecture
693 * specific callbacks, for dynamic registration and unregistration.
695 void kgdb_arch_exit(void)
698 for (i = 0; i < 4; i++) {
699 if (breakinfo[i].pev) {
700 unregister_wide_hw_breakpoint(breakinfo[i].pev);
701 breakinfo[i].pev = NULL;
704 unregister_nmi_handler(NMI_UNKNOWN, "kgdb");
705 unregister_nmi_handler(NMI_LOCAL, "kgdb");
706 unregister_die_notifier(&kgdb_notifier);
711 * kgdb_skipexception - Bail out of KGDB when we've been triggered.
712 * @exception: Exception vector number
713 * @regs: Current &struct pt_regs.
715 * On some architectures we need to skip a breakpoint exception when
716 * it occurs after a breakpoint has been removed.
718 * Skip an int3 exception when it occurs after a breakpoint has been
719 * removed. Backtrack eip by 1 since the int3 would have caused it to
722 int kgdb_skipexception(int exception, struct pt_regs *regs)
724 if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
731 unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
734 return instruction_pointer(regs) - 1;
735 return instruction_pointer(regs);
738 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
743 struct kgdb_arch arch_kgdb_ops = {
744 /* Breakpoint instruction: */
745 .gdb_bpt_instr = { 0xcc },
746 .flags = KGDB_HW_BREAKPOINT,
747 .set_hw_breakpoint = kgdb_set_hw_break,
748 .remove_hw_breakpoint = kgdb_remove_hw_break,
749 .disable_hw_break = kgdb_disable_hw_debug,
750 .remove_all_hw_break = kgdb_remove_all_hw_break,
751 .correct_hw_break = kgdb_correct_hw_break,